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PFAS模块
气-水界面吸附（溶质在土壤水与气-水界面之间的分配）
在评估动态包气带条件下多氟烷基物质（PFAS）的归趋和运移时，需要考虑气-水界面的吸附（溶质在土壤水与气-水界面之间的分配）[Silva et al., 2019, 2020, 2021]。在这种情况下，描述溶质在液相和气相之间分布的项被替换为描述溶质在气-水界面吸附的新项，如下所示：
其中Gamma是界面吸附浓度（即单位界面面积的质量或摩尔数，M/L²），Aaw是气-水界面面积，单位为[L²/L³]或[1/L]。气-水界面面积Aaw根据压力水头-饱和度关系，使用Bradford等人[2015]（亦见Bradford and Leij [1997]）的方程(8)计算：
其中Sigma_aw为气-水表面张力[M/T²]，Paw为毛细压力[M/L/T²]，theta_s为饱和含水量[L³/L³]，ro_w为水的密度[M/L]，g为重力加速度[L/T²]。用户可以在输入时指定一个附加常数，用于线性缩放界面面积Aaw。
界面吸附浓度（Gamma，单位界面面积的质量或摩尔数，M/L²）可以直接使用Freundlich-Langmuir吸附等温线计算：
其中Gamma_max [M/L²]为最大表面浓度（即溶解度极限），KH [线性吸附：L³/M¹；Freundlich吸附：L^(3Beta)/M^Beta]、Beta [-]和KL [L^(3Beta)/M^Beta]为经验系数。
土壤水力函数的浓度依赖性
HYDRUS采用与描述温度对土壤水力特性影响类似的缩放技术，来表达土壤水力函数的浓度依赖性。表面活性有机溶质对非饱和流的主要影响是通过土壤水压力水头对表面张力的依赖性实现的。表面张力对溶质浓度的依赖性根据Adamson和Gast (1997)以及Henry等人(2001)的描述进行描述。
其中a [L³/M¹]和b [-]为目标化合物的常数，sigma(c)为浓度c时的表面张力，sigma_0为参考浓度下的表面张力。
类似表达式用于考虑粘度作为溶质浓度的函数（Smith and Gillham, 1999）。
其中d [L³/M¹]和e [-]为目标化合物的常数，nu(c)为浓度c时的运动粘度，nu_0为参考浓度下的运动粘度。
测试示例
- 项目组：PFAS
- 描述：演示PFAS模块开发和验证的示例
- 获取方式：立即下载HYDRUS项目 (5.0 MB)
- 注意：以下发布的测试示例（Paper1a和Paper2a除外）是在5.01版本中创建的。此后（在5.03版本中），我们为AWI吸附实现了双点位吸附模型。因此，如果在HYDRUS 5.03或更高版本中运行以下示例，需要将FracA设置为1（在反应参数窗口中）。FracA是分类为类型-1（即具有瞬时吸附的位点）的AWI吸附位点的无量纲分数，如果仅考虑AWI平衡吸附（如这些示例中所做的），该值应等于1。
| 项目 | 描述 |
|---|
| 01SorbLin | 线性吸附测试 |
| 01SorbALin | 气相线性吸附测试 |
| 01SorbAWILin | AWI线性吸附测试 |
| 01SorbAWILin1 | AWI线性吸附测试，ScalAWI=2 |
| 02SorbNonLin | 非线性吸附测试，eta=0.9, beta=1.0 |
| 02SorbNonLin1 | 非线性吸附测试，eta=0.0, beta=1.2 |
| 02SorbNonLin2 | 非线性吸附测试，eta=0.0, beta=0.8 |
| 03AWINonLin | AWI非线性吸附测试，eta=0.9, beta=1.0 |
| 03AWINonLin1 | AWI非线性吸附测试，eta=0.0, beta=1.2 |
| 03AWINonLin2 | AWI非线性吸附测试，eta=0.0, beta=0.8 |
| 03AWINonLin3 | AWI非线性吸附测试：eta=0.0, beta=0.8，固相吸附：eta=0.2, beta=0.8 |
| 03AWINonLin_inv | AWI非线性吸附测试，eta=0.9, beta=1.0，反演 |
| Paper1a | Silva et al. (2020)；示踪剂及吸附到固相、AWI、固相+AWI的化学物质的垂向运移，一次降雨事件 |
| Paper12 | Silva et al. (2020)；示踪剂及吸附到固相、AWI、固相+AWI的化学物质的垂向运移，瞬态边界条件 |
主要参考文献
- Silva, J. A. K., J. Šimůnek, and J. E. McCray, A modified HYDRUS model for simulating PFAS transport in the vadose zone, Water, 12, 2758, 24 p., doi: 10.3390/w12102758, 2020. 下载PDF
- Silva, J. A. K., J. Šimůnek, and J. E. McCray, Comparison of methods to estimate air-water interfacial areas for evaluating PFAS transport in the vadose zone, Journal of Contaminant Hydrology, 247, 103984, 13 p., doi: org/10.1016/j.jconhyd.2022.103984, 2022. 下载PDF
- Silva, J. A. K., J. Šimůnek, J. L. Guelfo, and J. E. McCray, Simulated leaching of PFAS from land-applied municipal biosolids at agricultural sites, Journal of Contaminant Hydrology, 251, 104089, 14 p., doi: 10.1016/j.jconhyd.2022.104089, 2022. 下载PDF
- Biesek, B. J., A. Szymkiewicz, J. Šimůnek, A. Gumuła-Kawęcka, and B. Jaworska-Szulc, Numerical modeling of PFAS movement through the vadose zone: Influence of plant water uptake and soil organic carbon distribution, Science of the Total Environment, 935, 173252, 11 p., doi: 10.1016/j.scitotenv.2024.173252, 2024.
- Šimůnek, J., M. Šejna, G. Brunetti, and M. Th. van Genuchten, The HYDRUS Software Package ... Technical Manual I, Hydrus 1D, Version 5.0, PC Progress, Prague, Czech Republic, 334p., 2022. PDF (3.9MB)
- Šimůnek, J., M. Th. van Genuchten, and M. Šejna, The HYDRUS Software Package ... Technical Manual II, Hydrus 2D/3D. Version 5.0, PC Progress, Prague, Czech Republic, 283 p., 2022. PDF (3.6MB)
其他PFAS参考文献
- Guo, G., J. Zeng, and M. L. Brusseau, A mathematical model for the release, transport, and retention of per- and polyfluoroalkyl substances (PFAS) in the vadose zone, Water Resources Research, doi: 10.1029/2019WR026667, 2020.
- Stults, J. F., Y. J. Choi, C. E. Schaefer, T. H. Illangasekare, and C. P. Higgins, Estimation of transport parameters of perfluoroalkyl acids (PFAAs) in unsaturated porous media, Environmental Science & Technology, 56(12), 7963−7975, doi: 10.1021/acs.est.2c00819, 2022.
- Bierbaum, T., S. K. Hansen, B. Poudel, and C. Haslauer, Investigating rate-limited sorption, sorption to air-water interfaces, and colloid-facilitated transport during PFAS leaching, Environmental Science and Pollution Research, 19 p., doi: 10.1007/s11356-023-30811-2, 2023.
- Liao, S., U. Garza-Rubalcava, L. M. Abriola, H. E. Preisendanz, L. S. Lee, and K. D. Pennell1, Simulating PFAS transport in effluent-irrigated farmland using PRZM5, LEACHM, and HYDRUS-1D models, Journal of Environmental Quality, 12 p., doi: 10.1002/jeq2.20639, 2024.
- Stults, J. F., C. P. Higgins, T. H. Illangasekare, and K. Singha, Non-Fickian transport processes accelerate the movement of PFOS in unsaturated media, Journal of Contaminant Hydrology, 267, 104424, doi: 10.1016/j.jconhyd.2024.104424, 2024.
- Trobisch, K. M., D. M. Reeves, and D. P. Cassidy, Environmental fate and transport of PFAS in wastewater treatment plant effluent discharged to rapid infiltration basins, Water Research, 266, 122422, doi: 10.1016/j.watres.2024.122422, 2024.
- Umeh, A. C., R. Naidu, E. Olisa, Y. Liu, F. Qi, and D. Bekele, A systematic investigation of single solute, binary and ternary PFAS transport in water-saturated soil, Journal of Hazardous Materials, 461, 132688, doi: 10.1016/j.jhazmat.2023.132688, 2024.
- Vahedian, F., J. A. K. Silva, J. Šimůnek, and J. E. McCray, The influence of tension-driven flow on the transport of AFFF in unsaturated media, ACS ES&T Water, 11 p., doi: 10.1021/acsestwater.3c00611, 2024.
- Vahedian, F., J. A. K. Silva, J. Šimůnek, and J. E. McCray, Influence of kinetic air-water interfacial partitioning on unsaturated transport of PFAS in sandy soils, Science of the Total Environment, 957, 177420, doi: 10.1016/j.scitotenv.2024.177420, 2024.
- Garza-Rubalcava, U., C. Klevan, K. D. Pennell, L. M. Abriola, Transport and competitive interfacial adsorption of PFOA and PFOS in unsaturated porous media, Water Research, 268, Part B, 122728, doi: 10.1016/j.watres.2024.122728, 2025.
- Stults, J. F., C. E. Schaefer, T. MacBeth, Y. Fang, J. Devon, I. Real, F. Liu, D. Kosson, and J. L. Guelfo, Laboratory validation of a simplified model for estimating equilibrium PFAS mass leaching from unsaturated soils, Science of The Total Environment, 970, 179036, doi: 10.1016/j.scitotenv.2025.179036, 2025.
- Kolade, S. O., A. Ronen, T. Turkeltaub, C. Tsakiroglou, K. E. Strøyberg Klint, P. Das, and O. Dahan, Multi-compound PFAS transport in the unsaturated zone during infiltration cycles, Water Research, 124463, doi: 10.1016/j.watres.2025.124463, 2025.
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